Battery cell, battery module, and application of such a battery module

ABSTRACT

A battery cell, specifically a lithium-ion battery cell, having a prismatic battery cell housing (6), in which the electrochemical components of the battery cell (2) are accommodated, and further comprising a thermal equalization element (8), which is configured for the enhancement of thermal conductivity, which is arranged on a smallest lateral surface (64) of the battery cell housing (6), such that a region (9) of the smallest lateral surface (64) which is not covered by the thermal equalization element (8) at least partially encloses said thermal equalization element (8).

BACKGROUND OF THE INVENTION

The invention proceeds from a generic battery cell. The object of thepresent invention is also a battery module having such a battery cell.The invention further relates to the application of such a batterymodule.

From the prior art, it is known that battery modules can be comprised ofa plurality of individual battery cells, which can be mutuallyinterconnected in series and/or in parallel in an electricallyconductive manner.

Specifically in electrically-propelled vehicles (EV), hybrid electricvehicles (HEV) or plug-in hybrid electric vehicles (PHEV), batterymodules comprising energy-dense and high-power lithium-ion battery cellsor lithium-polymer battery cells, preferably comprised of approximatelyone hundred battery cells, are employed in order to be able to meetrising expectations for driving performance.

As a result of chemical conversion processes, lithium-ion battery cellsor lithium-polymer battery cells undergo heat-up, specifically duringthe output or take-up of electrical energy, such that, for the operationof high-performance battery cells of this type within a preferredtemperature range, it is further known that battery modules canincorporate a temperature-control system, which specifically ought toensure that the battery cells do not exceed a specific temperature.

It should be observed that the preferred service temperature oflithium-ion battery cells ranges from approximately 5° C. to 35° C.Moreover, service life declines consistently with effect from anoperating temperature from approximately 40° C., on the grounds ofwhich, in the interests of the fulfillment of requirements for anadequate service life, by means of the temperature-control system, thebattery cells are to be maintained in a thermally uncritical state,below a temperature of 40° C. Additionally, the temperature gradientbetween the different battery cells should not exceed 5K.

To this end, temperature-control systems which employ fluids flowingthrough cooling plates, such as, for example, water/glycol mixtures, areknown, for example, from the prior art.

It is further known from the prior art for a thermal equalization layer,also known as a “Thermal Interface Material” (TIM), to be arrangedbetween such cooling plates and the battery cells of the battery module.

To this end, printed publication WO 2012/147801 discloses a batterymodule having a plurality of battery cells and having a cooling plate,wherein a thermal equalization layer is arranged between the batterycells and the cooling plate.

Printed publication EP 2945217 discloses a cooling device for a batterypack, having at least two separate cooling elements arranged next to oneanother, each of which comprises a plurality of ducts which carry acoolant fluid for the evacuation of thermal energy. The cooling devicecomprises at least one tensioning unit, which compresses the at leasttwo cooling elements against one side of the battery pack, in theinterests of the improvement of thermal contact.

SUMMARY OF THE INVENTION

A battery cell according to the invention provides the advantage that areliable thermally-conductive connection of said battery cell to acooling plate can be configured over the service life thereof.

To this end, a battery cell is provided, which is specifically alithium-ion battery cell.

The battery cell comprises a prismatic battery cell housing, in whichthe electrochemical components of the battery cell are accommodated.

The battery cell further comprises a thermal equalization element, whichis configured for the enhancement of thermal conductivity.

The thermal equalization element is arranged on a smallest lateralsurfaces of the battery cell housing, such that a region of the smallestlateral surface of the battery cell housing which is not covered by thethermal equalization element at least partially encloses said thermalequalization element.

By means of the measures described in the dependent claims, advantageousfurther developments and improvements of the device disclosed in theindependent claim are possible.

At this point, it should be observed that a prismatic battery cellhousing specifically comprises six lateral surfaces, wherein directlyadjoining lateral surfaces are preferably configured in a mutuallyperpendicular arrangement, and opposing lateral surfaces are preferablyarranged in parallel with each other. Specifically, opposing lateralsurfaces are configured here with equal dimensions.

These six lateral surfaces of the prismatic battery cell housingpreferably delimit an interior space of the battery cell housing, whichaccommodates the electrochemical components of the battery cell.

Prismatic battery cells undergo deformation in the course of theirservice life, specifically during charging and discharging, wherein themutually opposing largest lateral surfaces of the prismatic battery cellhousing are configured to deform outwards, averted from the interiorspace which accommodates the electrochemical components of the batterycell, and the mutually opposing smallest lateral surfaces of theprismatic battery cell housing are configured to deform inwards towardsthe interior space which accommodates the electrochemical components ofthe battery cell.

Advantageously, the battery cell incorporates a first region of thesmallest lateral surface which is not covered by the thermalequalization element, and a second region of the smallest lateralsurface which is not covered by the thermal equalization element.

The thermal equalization element is thus further arranged between thefirst region and the second region.

Accordingly, in addition to an enhancement of the thermally-conductiveconnection of the battery cell to a cooling plate, it is also possibleto reduce the requisite quantity of material for the thermalequalization element.

Specifically, it is thus possible to arrange the thermal equalizationelement in a region of the smallest lateral surfaces which deforms overthe service life of the battery cell according to the invention, wherebya reliably thermally-conductive connection can also be configuredbetween the deformed region and a cooling plate.

Appropriately, the first region and the second region are configured ina mutually parallel arrangement.

It is thus possible for the first region and the second region, andspecifically also the thermal equalization element, to be adapted to thesmallest lateral surface of a prismatically configured battery cellhousing.

Moreover, it is also appropriate if the uncovered region entirelycircumferentially encloses the thermal equalization element.

It is thus possible to arrange the thermal equalization element in aregion of the smallest lateral surfaces which undergoes deformation overthe service life of the battery cell according to the invention, as aresult of which, preferably, a reliably thermally-conductive connectioncan also be configured between the deformed region and a cooling plate.

Overall, the thermal equalization element thus undergoes reducedexpansion compared to the smallest lateral surface.

It is advantageous if the uncovered region is arranged directlyadjacently to an edge of the battery cell housing which delimits thesmallest lateral surface.

It is thus possible for the thermal equalization element not to bearranged on an edge of the battery cell housing, in consequence whereofthermal contact between the battery cell housing and a cooling plate canbe enhanced on the grounds that, as a result of the deformation of theprismatic battery cell housing, thus-configured, linear contacts betweenthe battery cell housing and the cooling plate or a contact element canbe prevented.

According to an advantageous aspect of the invention, the thermalequalization element comprises a surface which engages in contact withthe battery cell housing. Preferably, this is configured as a curvedsurface. Specifically, the curved surface of the thermal equalizationelement is adapted to the deformed smallest lateral surface of thebattery cell housing, such that the largest possible contact surface isachieved.

Accordingly, the thermal equalization element can be adapted to theage-related deformation of the battery cell housing, such that improvedthermal conduction is possible.

Preferably, the thermal equalization element is joined to the batterycell housing. Specifically, the thermal equalization element isadhesively bonded to the battery cell housing.

A reliable connection can thus be configured between the thermalequalization element and the battery cell housing.

Appropriately, the thermal equalization element is configured forelastic and/or plastic deformation.

It is thus possible for the thermal equalization element to beconsistently adapted to the age-related deformation of the battery cellhousing.

It is further appropriate if the thermal equalization element isconfigured of an electrically-insulating material.

It is thus possible for an electrical insulation to be configuredbetween the battery cell and a cooling plate.

Naturally, an electrically-insulating contact element can also beprovided.

Appropriately, the thermal equalization element has a thermalconductivity with a value greater than or equal to 0.4 watts per meterand per degree kelvin (W/mK).

Preferably, the thermal equalization element has a thermal conductivitywith a value of 1 W/mK.

Specifically, the thermal equalization element has a thermalconductivity with a value of 2 W/mK.

A reliable thermal conductivity can be configured accordingly.

The invention further relates to a battery module having a battery cellaccording to the invention.

The battery module further incorporates a cooling plate.

The battery cell is connected to the cooling plate in athermally-conductive manner.

The thermal equalization element is further arranged between thesmallest lateral surface of the battery cell and the cooling plate.

The invention further relates to the application of a battery moduleaccording to the invention for the maintenance of thermal conductivitybetween the battery cell and the cooling plate in the event of anage-related and/or service-related deformation of the battery cellhousing.

Specifically, prismatic battery cell housings undergo deformationincreasingly with increasing age, as a result of which it is possible,by means of a battery cell according to the invention, to maintainthermal conductivity between the battery cell and the cooling plate.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are represented in the drawings,and are described in greater detail in the following description.

In the drawings:

FIG. 1 shows a perspective representation of one form of embodiment of abattery module according to the prior art,

FIG. 2 shows a schematic representation of one form of embodiment of aprismatic battery cell, in an undeformed state and in a deformed state,

FIG. 3 shows an overhead view of a representation of athermally-conductive contact region between a cooling plate of a batterymodule and the battery cells thereof, according to the prior art,

FIG. 4 shows one form of embodiment of a battery cell according to theinvention, viewed in the direction of a smallest lateral surface,

FIG. 5a shows a battery cell with no thermal equalization element,according to the prior art,

FIG. 5b shows one embodiment according to the invention of a batterycell with a thermal equalization element,

FIG. 6 shows one form of embodiment of a plurality of thermalequalization elements for a cooling plate of a battery module, and

FIG. 7 shows a schematic representation of one form of embodiment of abattery module according to the invention.

DETAILED DESCRIPTION

FIG. 1 shows a schematic representation of a perspective view of oneform of embodiment of a battery module 100 according to the prior art.

The battery module 100 according to the prior art comprises a pluralityof battery cells 200, the respective voltage taps 300 of which can bemutually electrically connected in series and/or in parallel.

The battery module 100 further comprises a cooling plate 400, which isconnected to the battery cells 200 of the battery module 100 in athermally-conductive manner.

FIG. 2 shows a schematic representation of a battery cell 200 having aprismatic battery cell housing 600.

The battery cell housing 600 is shown in an undeformed state, which isrepresented by the solid lines 601.

The battery cell housing 600 is additionally shown in a deformed state,which is represented by the broken lines 602.

Specifically, the undeformed state represents a state of the batterycell housing 600 at the start of the service life of the battery cell200, and the deformed state represents a state of the battery cellhousing 600 towards the end of the service life of the battery cell 200.

Such deformation of the battery cell 200 can also occur during thecharging or discharging of the battery cell 200, such that deformationcan also be dependent upon the state of charge.

From FIG. 2, it can be seen that the battery cell 200 comprises largestlateral surfaces 603, which are arranged in opposition to each otherand, in the undeformed state, are configured in a mutually parallelarrangement. From FIG. 2, it can further be seen that the battery cell200 comprises smallest lateral surfaces 604, which are arranged inopposition to each other and, in the undeformed state, are alsoconfigured in a mutually parallel arrangement.

Over the service life of the battery cell 200, the prismatic batterycell housing 600 is deformed, such that the battery cell housing 600,for example, initially assumes the undeformed state represented by meansof the solid lines 601, and latterly assumes the deformed staterepresented by means of the broken lines 602.

From FIG. 2, it can be seen that the largest lateral surfaces 603,considered from an interior space 605 for the accommodation of theelectrochemical components of the battery cell 200, are deformedoutwardly averted from the latter, and that the smallest lateralsurfaces 604, considered from the interior space 605 for theaccommodation of the electrochemical components of the battery cell 200,are deformed inwardly towards the latter.

FIG. 3 shows an overhead view of a cooling plate 400 of a battery module100 according to the prior art. The battery cells 200 represented inFIG. 1 are not visible.

FIG. 3 additionally shows a contact region 700 configured between thebattery cells 200, which specifically assume the deformed staterepresented in FIG. 2, and the cooling plate 400 of the battery module100 or between the battery cells 200, which specifically assume thedeformed state represented in FIG. 2, and a foil-type contact element1300, which can additionally be arranged between the battery cells 200and the cooling plate 400.

It can be seen that the contact region 700 is comprised of a pluralityof linearly-configured and mutually parallel contact points 701.

Specifically, in comparative terms, the contact region 700 covers only avery small proportion of the cooling plate 400.

This is dictated by the fact that, in an arrangement of a battery cell200 in the deformed state represented in FIG. 2, as a result of thedeformation thus configured, only edges 606 thereof can engage incontact with the cooling plate 400 or the contact element 1300.

Overall, in comparative terms, thermal conductivity between the coolingplate 400 and the battery cell 200 is substantially impaired as aresult.

FIG. 4 represents one form of embodiment of a battery cell 2 accordingto the invention, viewed in the direction of a smallest lateral surface64.

The battery cell 2 essentially corresponds to the battery cell 200represented in FIG. 2.

Specifically, the battery cell 2 also comprises a prismatic battery cellhousing 6, which accommodates the electrochemical components of thebattery cell 2.

The battery cell housing 6 also specifically comprises mutually opposingsmallest lateral surfaces 64, and mutually opposing largest lateralsurfaces 63, which are not visible in FIG. 4.

The battery cell 2 represented in FIG. 4 only differs specifically fromthe battery cell 200 represented in FIG. 2, in that the battery cell 2further comprises a thermal equalization element 8, which is designed toincrease thermal conductivity.

The thermal equalization element 8 is arranged on the smallest lateralsurface 64 of the battery cell housing 6.

The thermal equalization element 8 is further arranged on the smallestlateral surface 64 of the battery cell housing 6 such that a region 9 isconfigured which is not covered by the thermal equalization element 8,and which at least partially encloses the thermal equalization element8.

From FIG. 4, it can further be seen that the battery cell 2 comprises afirst region 91 of the smallest lateral surface 64 which is not coveredby the thermal equalization element 8, and a second region 92 of thesmallest lateral surface 64 which is not covered by the thermalequalization element 8.

The thermal equalization element 8 is preferably further arrangedbetween the first region 91 and the second region 92.

From FIG. 4, it can further be seen that the first region 91 and thesecond region 92 are configured in a mutually parallel arrangement.

Specifically, FIG. 4 also shows that the uncovered region 9 entirelycircumferentially encloses the thermal equalization element 8.

Additionally, in FIG. 4, a broken line represents one edge 66 which isnot deformed over the service life of the battery cell 2, specificallyduring charging and discharging, and, in other words, is configured toan inflexible or rigid design.

Conversely, the region of the smallest lateral surface 64 which iscovered by the thermal equalization element 8 specifically undergoesdeformation over the service life of the battery cell 2, as represented,for example, in FIG. 4.

Specifically, it is understood that the edge 66 delimits the smallestlateral surface 64.

Thus, according to the exemplary embodiment of the battery cell 2represented in FIG. 4, the uncovered region 9 is arranged directlyadjacently to the edge 66 of the battery cell housing 6.

FIG. 5a shows a battery cell 200, which is configured in a deformedstate of the battery cell housing 600 according to FIG. 2, having acontact element 1300 according to the prior art. It can clearly be seenthat, specifically, the contact element 1300 only engages in contactwith the battery cell 200 on the edges 606 thus configured. Accordingly,in comparative terms, thermal conduction between the battery cellhousing 600 and a cooling plate 400, which is not represented in FIG. 5a, is significantly reduced. Specifically, the linear contact points 701represented in FIG. 3 are constituted.

FIG. 5b shows one embodiment of a battery cell 2 according to theinvention, which is configured in a deformed state of the battery cellhousing 6 according to FIG. 2, having a thermal equalization element 8.A contact element 13, which can additionally be provided, can also beseen.

It can clearly be seen that, by means of the thermal equalizationelement 8, a contact surface can be configured between the thermalequalization element 8 and the battery cell housing 6.

Moreover, a comparatively enlarged contact surface can be configuredbetween the thermal equalization element 8 and the contact element 13.

It is thus possible, specifically in comparison with the left-handrepresentation shown in FIG. 5b , to significantly increase thermalconduction between the battery cell housing 6 and a cooling plate, whichis not represented in FIG. 5 b.

FIG. 5b indicates that the thermal equalization element 8 has a surface10 which engages in contact with the battery cell housing 6.

Specifically, the surface 10 is in contact with the smallest lateralsurface 64 of the battery cell housing 6.

It will further be seen that the surface 10 is configured with acurvature, such that the surface 10 is adapted to the profile of thedeformed smallest lateral surface 64.

The surface 10 can, for example, be adhesively bonded to the batterycell housing 6.

The thermal equalization element 8 according to FIG. 5b is configured inan elastically and/or plastically deformable manner. This provides theadvantage that the thermal equalization element 8, even over the servicelife of the battery cell 2, can be adapted to the deforming battery cellhousing 6, and specifically to the deforming smallest lateral surface64.

Moreover, the thermal equalization element 8 can be configured of anelectrically insulating material, whereby the prevention of anyelectrical contacting between the cooling plate 4 and the battery cellhousing 6 would thus be possible.

It is further possible for the contact element 13 to be configured of anelectrically insulating material.

FIG. 6 shows one form of embodiment of a plurality of thermalequalization elements 8 which are arranged, for example, on a carrierfilm 11.

A carrier film 11 of this type can be bonded to a cooling plate 4 of abattery module 1, such that the simple manufacture of a battery module 1is possible.

The carrier film 11 can be configured, for example, of an electricallyinsulating material.

Specifically, the carrier film 11 can also correspond to the contactelement 13 described in FIG. 5 b.

Naturally, it is also possible for the thermal equalization elements 8to be positioned separately on the respective battery cells 2, orpositioned separately on the cooling plate 4.

FIG. 7 shows a schematic representation of one form of embodiment of abattery module 1. The battery module 1 comprises a plurality of batterycells 2 according to the invention, each comprising a thermalequalization element 8.

The battery module 1 further comprises a cooling plate 4 which isconnected to the battery cells 2 in a thermally conductive manner, andis specifically arranged adjacently to the smallest lateral surface 64of the battery cells 2 in each case.

A contact element 13 can additionally be configured, which is notvisible in FIG. 7.

The thermal equalization element 8 is arranged respectively between thesmallest lateral surfaces 64 of the battery cell 2 and the cooling plate4.

Additionally, the battery module 1 can further comprise a tensioningelement 12, which compresses the cooling plate 4 against the respectivethermal equalization elements 8, such that thermal conductivity can bemaintained and tolerances can be compensated.

The invention claimed is:
 1. A battery module comprising a plurality ofbattery cells (2) each having a prismatic battery cell housing (6), inwhich electrochemical components of the battery cell (2) areaccommodated, wherein the plurality of battery cell housings (6) arearranged next to one another and in abutment with one another along adirection, wherein the battery module further includes a plurality ofthermal equalization elements (8) configured to conduct heat from thebattery cell housings (6) to a cooling plate, wherein each of theplurality of battery cells (2) is associated with and coupled to adifferent one of the plurality of thermal equalization elements (8),such that for each battery cell (2), the associated thermal equalizationelement (8) is in abutment with a portion of a smallest lateral surface(64) of the battery cell housing (6), such that an uncovered region (9)of the smallest lateral surface (64), on which the thermal equalizationelement is not arranged, substantially circumferentially surrounds saidthermal equalization element (8) at a location where the thermalequalization element (8) is in abutment with the lateral surface (64),and such that the smallest lateral surface of the battery cell and thethermal equalization element are configured to enhance thermal contactbetween the battery cell housing and the cooling plate as the batterycell deforms, wherein the thermal equalization elements (8) are separatefrom one another and spaced apart from one another along the direction.2. The battery module according to claim 1, wherein for each batterycell (2), the uncovered region includes a first region (91) along thesmallest lateral surface and a second region (92) along the smallestlateral surface, wherein for each battery cell (2), the associatedthermal equalization element (8) is further arranged between the firstregion (91) and the second region (92), such that the first and secondregions are on opposing sides of the thermal equalization element. 3.The battery module according to claim 2, characterized in that the firstregion (91) and the second region (92) are configured in a parallelarrangement.
 4. The battery module according to claim 1, characterizedin that for each battery cell (2), the uncovered region (9) entirelycircumferentially surrounds the associated thermal equalization element(8) at the location where the thermal equalization element (8) is inabutment with the lateral surface (64).
 5. The battery module accordingto claim 1, characterized in that the uncovered region (9) is arrangeddirectly adjacently to an edge (66) of the battery cell housing (6)which delimits the smallest lateral surface (64).
 6. The battery moduleaccording to claim 1, characterized in that for each battery cell (2),the associated thermal equalization element (8) comprises a surface (10)which engages in contact with the battery cell housing (6) and which isconfigured as a curved surface.
 7. The battery module according to claim1, characterized in that for each battery cell (2), the thermalequalization element (8) is joined directly to the battery cell housing(6) by adhesive bonding.
 8. The battery module according to claim 1,characterized in that each thermal equalization element (8) isconfigured for elastic and/or plastic deformation.
 9. The battery moduleaccording to claim 1, characterized in that each thermal equalizationelement (8) is configured of an electrically-insulating material. 10.The battery module according to claim 1, characterized in that eachthermal equalization element (8) has a thermal conductivity with a valuegreater than or equal to 0.4 W/mK.
 11. The battery module according toclaim 1, characterized in that each thermal equalization element (8) hasa thermal conductivity with a value of 1 W/mK.
 12. The battery moduleaccording to claim 1, characterized in that each thermal equalizationelement (8) has a thermal conductivity with a value of 2 W/mK.
 13. Amethod for maintaining thermal conductivity between a battery cell (2)and a cooling plate (4) in the event of an age-related and/orservice-related deformation of a battery cell housing (6) containing thebattery cell, the method comprising providing a battery module accordingto claim 1, wherein for each battery cell (2), the thermal equalizationelement maintains contact with the battery cell housing by deforming asthe battery cell housing deforms to enhance thermal contact between thebattery cell housing and the cooling plate.
 14. The battery moduleaccording to claim 1, further comprising a carrier film (11), whereineach of the plurality of thermal equalization elements (8) extends fromthe carrier film (11) to the lateral surface (64) of one of the batteryhousing (6).
 15. The battery module according to claim 1, furthercomprising the cooling plate (4), and a tensioning element (12)configured to compress the cooling plate (4) against the plurality ofthermal equalization elements (8).
 16. A battery module comprising asingle battery cell having a prismatic battery cell housing (6), whereinthe prismatic battery cell housing (6) includes a first wall, a secondwall, a third wall, a fourth wall, a fifth wall, and a sixth wall,wherein the first wall, the second wall, the third wall, the fourthwall, the fifth wall, and the sixth wall together define a singleinterior space in which electrochemical components of the battery cell(2) are accommodated, wherein the battery module further includesthermal equalization element (8) configured to conduct heat from thebattery cell housing (6) to a cooling plate, wherein the thermalequalization element is in abutment with a portion of a smallest lateralsurface (64) defined one of the first wall, the second wall, the thirdwall, the fourth wall, the fifth wall, or the sixth wall, such that anuncovered region (9) of the smallest lateral surface (64) on which thethermal equalization element is not arranged substantiallycircumferentially surrounds said thermal equalization element (8) at alocation where the thermal equalization element (8) is in abutment withthe lateral surface (64), such that the smallest lateral surface of thebattery cell and the thermal equalization element are configured toenhance thermal contact between the battery cell housing and the coolingplate as the battery cell deforms.
 17. The battery module according toclaim 16, wherein the uncovered region includes a first region (91) onthe lateral surface (64) and a second region (92) on the lateral surface(64), wherein the thermal equalization element (8) is further arrangedbetween the first region (91) and the second region (92), such that thefirst and second regions are on opposing sides of the thermalequalization element.
 18. The battery module according to claim 16,wherein the thermal equalization element (8) comprises anelectrically-insulating material.
 19. The battery module according toclaim 16, wherein the smallest lateral surface (64) is defined by thefirst wall, and wherein the first wall is parallel to an opposite,second wall.